1. Technical Field
The present invention relates to an electronic device substrate, an electronic device, a method of manufacturing an electronic device substrate, a method of manufacturing an electronic device, and an electronic apparatus.
2. Related Art
In general, an electronic device, such as a liquid crystal display, an EL display, or a fingerprint sensor, includes a TFT substrate having a plurality of thin-film transistors. The TFT substrate is provided with a connection terminal which connects a driver IC for driving thin-film transistors to the TFT substrate. Alternatively, the TFT substrate is provided with a driver circuit for driving thin-film transistors, and a connection terminal which connects an external component to be connected, for supplying electrical signals to the driver circuit, to the TFT substrate.
As the method for connecting a TFT substrate to an external component to be connected, such as a driver IC, a method is known in which the two are thermocompression-bonded to each other through an anisotropic conductive film, for example, as disclosed in JP-A-2008-218542. In an anisotropic conductive film, conductive particles are dispersed in a film composed of a thermosetting adhesive. When the film is subjected to thermocompression bonding in the thickness direction, the thermosetting adhesive is fluidized and the conductive particles in the film are captured and compressed between a connection terminal of a TFT substrate and a connection terminal of a driver IC. The resulting deformation is maintained by the thermoset adhesive, thus establishing electrical connection between the terminals.
Furthermore, recently, JP-A-2008-276212 has disclosed use of a flexible resin substrate as a TFT substrate in order to realize flexible electronic devices.
However, in order to form thin-film transistors, insulating films, such as an underlying protective film, a gate-insulating film, an interlayer insulating film, a planarizing film, and a top protective film, are formed on the TFT substrate. These insulating films are usually composed of an inorganic material (e.g., silicon oxide or silicon nitride). In the case where a flexible resin substrate is used as the TFT substrate and an inorganic material is used for the insulating films, since the TFT substrate and an external component to be connected are thermocompression-bonded to each other with an anisotropic conductive film therebetween, the TFT substrate is placed under the environment of high temperature (e.g., 150° C. to 200° C.) and high pressure (e.g., 2 to 5 MPa). In such a case, the flexible resin substrate is deformed due to pressure, and cracks or the like occur in the insulating films. As a result, wiring disposed on the inorganic insulating films may be disconnected, resulting in a decrease in production yield.